Art of irrigating and fertilizing soil



Patented Aug 3,, 1%

aosassa and or IRRHGATING Ann FEWEHLHZHNG Herbert Henderson Porter, (llarendon, Va.

N o Drawing.

matters which are converted by alkaline waters into diffusible icolloid condition, and also the presence of alkalis in irrigating water in contact with soils containing 'silicic acid ions effects a conversion of the soil which often is harmful to plants being grown thereon. Difiusion of colloids often harms the plants as their roots suffer from lack of air, and the usual processes oinitrification ally acid soilsmaybe harmed by alkaline waters? and alkaline soils "are rendered more alkaline by the action of'such Waters. Furthermore, it has not heretofore been'possible, by simple means, to correct the pH value of the soils' to adapt them for particular crops, while at the same time fur nishing the soils with'proper and sufiicient fertilizer value. 1,

The copendin'g application of William O. Sweek, Serial No. 731,972,flled JuneZZ 1934, now U.- S. Letters Patent 2,028,172, in""wliich thiefpresent applicant is a co-assignee, describes the irrigation and fertilization of soils by using the stored power of water for producing electricity, em-

the fixed nitrogen into water,and using the power of the stored water also for moving the charged water to the soil. This method is' particularly applicable for fixing the nitrogen by the electric arc method, and this leads ultimately to the formation of nitric acid ions in the water, so that a relatively alkaline water is at least in part acidified, and thus also alkaline soils in irrigation areas are prevented from going'back from the effects of'constantly'employing water of ex cessive alkalinity for irrigation.

The electric arc method, however, has the difficulty of producing a ration of fertilizer which is proportioned to the acidifying or neutralizing effect, so that'it is best applied to alkaline waters or for cultivating acid-manufacturing plants: and has the difiiculty of demanding a large expenditure of energy (around 61,000 kilowatt hours per ton of fixed nitrogen) for the quantity of fertilizer produced.

The present invention proposes to employ the energy of the water for producing ammonia and for converting the same in part to nitric acid, and then to convey the nitrogen gases,'as ammonium cannot go on in proper form. Thus, even naturploying the electricity to fix nitrogen, introducing v Application January 21, 1936, Serial No. carer (Gil. ill-58) and nitric acid ions, to the soil by the irrigation water. By properly dosing the ammonia and nitric acid, a close control of the relative acidity or alkalinity may be eifected, along with a proper pro'portioning of the relative pH value and of the 5 nitrogenous fertilizer value independently of one another. Further, since irrigation projects are I usually so arranged that quantities of electrical energy may be produced cheaply, it is particularly advantageous to use this energy also for producing the initial materials from which the ammonia is, formed, and for effecting the necessary compressions and heatings of gases and gaseous'mixe tures for maintaining the through-put eificiency of the plant According to this invention, water is impounded by a dam, and then passed as usual through an energy convertor, such. as a turbo-generator plant for producing electrical encrgy.- The water from the turbine-outfall is usually still above the level of the fields to be irrigated: or, if not, energy from the impounded water may be employed to raise a portion of the same to the necessary head for irrigation purposes.

This electrical energy is then employed in.- part as directcurrent for operating an electrolytic battery for producing hydrogen and oxygen from water in the usual way and by any suitable apparatus which permits collecting the separated gases. 30

A further part of this electrical energy is employed for working the compressors of an airliquefaction plant, whichmay be of the Claude or Linde type; and is operated in conjunction with a still and arranged for counter-current flow of the hot compressed air with respect to the distilling liquid and gases. That is, the liquefied air is permitted to distill fractionally whereby the oxygen and nitrogen are separatedand each is reheated substantially to atmospheric'temperature before it is discharged. The quantity of energy demanded is therefore reduced, as the heat extracted from hot compressed gases is essentially recoveredin restoring the separated gases to atmospheric temperature.

In conjunction therewith, the electrolytic plant may be operated to deliver a greater quantity of hydrogen than is required for conversion to ammonia, and this hydrogen (without preliminary drying, for example) may be mixed with air and the mixture burned to provide an increment of nitrogen. This nitrogen is then dried by successively passing over quick lime and calcium chloride or other hygroscopic matters which are later reavailable. I

Hydrogen from the electrolytic apparatus is dried and mixed with the dry nitrogen from the still and/or air burner and is then pumped through a heater -and over a catalyst capable ofcombining the hydrogen and nitrogen to form ammonia. Such a catalyst may for example be iron oxide with promoters such as potassium and aluminum oxides mixed therewith. The percentage of ammonia formed is greater at lower temperatures such as 200 degrees C., but no large yield is formed. It is therefore preferred to operate at a temperature of around 450 degrees C., and up to 700 degrees C.; with a pressure of 100 to 900 atmospheres. The action is exothermic,

and the temperature is preferably controlled by varying the velocity of the gases on their way through the catalyst. It is preferred to pass a relatively large volume, in order to keep the temperature at the desired point. For example, .at a pressure of 300 atmospheres, and passing at a space velocity rate of 10,000 (i. e. the ratio of cubic feet of gas per cubic foot of catalyst), the

per cent. This may be increased up'to 100,000, but the preferable operating space velocity is around 20,000, under normal conditions.

As a result of this action, the eilluent gases con- 40 pumped back, with suitable drying, and re-introduced with fresh incoming gases, for a further catalytic action.

.The trickle liquid may then be utilized directly for introduction into water of acid or neutral nature, and then passed on to the soil. This is a manner of operating when the present inven-' tion is used throughout the day.

If, however, the present plant is being operated during the night, to take advantage ofof!- peak loading on the generator equipment, then the trickle liquid may be re-circulated and stored until required, at which time it is dosed into the water passing to the soils, under similar conditions.

If the water is not highly alkaline, it is found that portions of the ammonia are oxidized during passage to the 'soil, and during the period prior to their acceptance by the plants.

It is, however, preferred to convert at least a 60 part of the ammonia to nitric acid form. It is found possible to utilize a fertilizing mixture in which 60 per cent. of the nitrogen is in ammonia form, while the remaining 40 per cent. is present as a nitrate nitrogen.

For this purpose, the trickle liquors are preferably re-circulated through the tower until a strong solution of aqua ammonia is produced, which is intermittently passed into the still, and the still heated preferably by the electric energy. The ammonia is given off as a gas, and preferably after drying is then mixed with oxygen from the electrolytic cell and from the liquefaction-still apparatus, and usually with a further quantity of 75 air. In order to convert all of the ammonia in efficiency of ammonia formation is around 25.

a,oas,sso generated by heating by the' electrical energy nitric acid, it is n to provide more oxygen than is obtained from electrolyzing water to produce the necessary hydrogen and from the distillation. of liquid air for producing the corresponding nitrogen. This deficit of oxygen may be obtained by introducing air, as stated, or by using excess hydrogen, as stated above,'to burn out air in producing nitrogen. The oxygen corresponding to this excess hydrogen is therefore available for burning ammonia.

For burning the ammonia, the mixed ,vapors containingammonia and oxygen are then pumped through a heater and through an oxidizing cataly'st. The pressure employed controls the operation in part: and the temperature is preferably around 800 to 1,000 degrees C. As a catalyst, it

is preferred to employ a fine mesh of platinum wire, heated electrically: this platinum isusable for long periods of time, as the operations do not lead to the introduction of any-considerable poisons for the catalyst.

- The eiiluent gases from the oxidizing catalyst maining oxygen into the eiiluent gases from the catalyst. In this way, also, a proper dosing of ammonia and nitrogen oxide may be effected.

. The eiiluent gases from the oxidizing catalyst are then passed into a trickle tower, or otherwise brought into contact with the water, or a portion 'of the water, to be utilized for irrigation. As a result of this action, the ammoniais dissolved in this water and a reaction also occurs between the nitrogen oxide gases which leads to the formation of nitric acid which also dissolves in the water, so that the water contains both ammonium and nitric acid ions. Theoxide gas reactionleads to the production, usually, of a further quantity of nitric oxide, but this is in turn oxidized by contact with the air or excess oxygen present, and in turn forms the peroxide and a a further quantity of nitric acid ions. To facilitate this reaction and re-oxidization, it.is preferred to maintain the gases in contact with the water and with one another'for a considerable time, and this may be effected by using an appropriate trickle tower or by passing the gases into the turbine infall or outfall.

Thus, by controlling the proportion of ammonia which is oxidized, by determining the temperature, velocity, and oxygen content present, an exact rationing of ammonia to nitric nitrogen may be effected in consonancewith the relative alkalinity or acidity of the water or soil; while the actual fertilizing value may be increased or decreased irrespective of the acidifying or almonimand eliminating the ammonia from the nitrogen and hydrogen gases, which may then be returned in their mixture to the inlet of the catalyst, chamber by a pump capable of compensating the pressure drop through the catalyst chamber and associated conduits. The ammonia passes from the eliminators to a receiver at a temperature of around 100 degrees 0., and

.' accuses synthesizing catalyst chamber, while the ammonia itsellis' heated and vaporized and then is mrmitted to flow through a iurther heater, alter being mixed with the necessary quantity oi oxygen as stated above, and thus into the oxidizing catalyst chamber.

It is particularly preferred to accomplish a partial oxidationoi the ammonia, as water con taining both ammonium and nitric acid ions is highly advantageous for ie'rtilimng purposes. With alkaline soils and alkaline water, the conditions of oxidation'are so maintained that the viding excess or om gen, using proper high temperatures, and thus assuring a high acidifying value of the gases.

According to the plants to be cultivated, difterent relative proportions of nitrogen fertilizer may be introduced, as pointed out in the aforesaid patent: and it will be noted that the present invention permits the control of acidity irrespective of the nitrogen content, within the generated by the mixture of ammonia and nitrogenntoxide gases at the operating equilibrium p0 It is obviousthat the invention is likewise ap plicable in other instances where hydrogen and nitrogen are formed and combined, and then at least in part oxidized to provide a source of nitric acid ions for introduction into irrigating water. As set forth above, the energy of the impounded water is therefore also available for moving this charged water to the soil to be irrigated, in the usual ways. It is feasible to operate a small capacity plant throughout the day, and to store up the converted nitrogen as aqua ammonia 40 and/or nitric acid, in ponds prepared for that urpose, and then to introduce these concentrated liquors, with appropriate prior conversion if necessary for the particular gas in determining the content of nitrogen and the acidifying values. M in the water which is being passed down the hurries to the particular held. Thus. the content, both with respect to nitrogen and with respect to aci i y, may be varied for difl'erent fiuines and for the same flumes on diflerent days.

As set out in the aforesaid patent, the delivery of'the nitrogenated water is preferably interrupted at the beginning. of the seeding or fruiting season; in order to assure proper iruiting or seeding of the plants. Since the present process 55 lends itself to accurate proportioning of acidi or alkalinity, it is thusfeasible to cultivate the crops with a maximum accuracy of sat a t of gen demand and by use of a water oi P p r pH value, by simple means and by emso p oyment or current which can, be obtained ply at irrigation projects.

It is obvious that other changes may be made 1 in the inventirmv without departingv from the scope oi the appended claims. v

I claim: 1

- 1. The method or irrigating which comprises storing, water, employing energy oithe stored water for generating electricity, employing the electricity for electrolyzing water to produce hydrogen, combining thehydrogen with nitrogen to produce ammonia, oxidizing the ammonia to nitrogen oxide and-passing theproducts into water from the storage'to torm'nitric acid, and moving the treated water for irrigation by energy oi! the storage head, while controlling the equilibrium point is closely approached by prolimits of the acidiiying powers which can be,

2. The, method of irrigating which comprises producing ammonia oxidizing apart of the ammonia to nitrogen oxide, passingthe oxidation products into water, and utilizing the water-vior irrigation, while controlling the. ration of nitric oxide and ammonia and the {pH-ot-the water according to the needs or plants and soil.

'3. The method of irrigating which comprises producing ammonia, oxidizing a partot the andmonia to nitrogen 'oiddepassing the oxidized product and amnioniainto water, and utilizing the water for irrigation, while controlling the ration of nitric oxide and ammonia and the pH of the water according to the needs of plants and soil. t. The method of irrigating allsaline soils, which comprises producing ammonia, oxidizing the ammonia to nitrogenoxide, passing the oxidized product into water to effect a relative acidiiication of the water, and passing the treated water to the soil, while controlling the ration of nitrogen oxide and the pH of the water according to the needs of plants and soil.

5. The method of irrigating'soil with originally alkaline water, which comprises producing ammonia, oxidizing the ammonia to nitrogen oxide, mssing the omdized product into water to reduce the aliralinityoi the water, and passing the treated water to the soil, while controlling the ration oi nitrogen oxide and the pH of the water according to the needs of plants and soil; 6. The method of irrigating alkaline soils with originally alkaline water, which comprises PTO". ducing ammonia, partially oxidizing the ammonlato nitrogen omde, passing the mixture oi nitrogen gases into wawr to form an acid solution oi ammonium nitrate, and passing the treated water to the soil, while controlling the ration of ammonium nitrate and the pH of the water according to the needs of the plants and soil;

- ration of nitric acid thus-supplied accordingrto.

the needs of plants and soil.

7. The method oi irrigating, which comprises storing water, employing energy of the water for generating electricity, employing the electricity 'ior electrolyzing water to produce hydrogen and oxygen, iractionally separating air into nitrogen and oxygen, combining the hydrogen and nitrogen to form ammonia, oiddizing the ammonia by the oxygen produced in the electrolysis andsepa ration totorm nitrogen crude, and utilizing the water for irrigatiomwhiie controlling the ration of nitrogen oxide and the pH of the water according to the needsoi plants and soil.

s. The method of irrigating soils, which comprises storing water, employing energy of the water for generating electricity, employing the electricity for making ammonia and oxidizing the same to nitrogen oxide, passing a mixture of ammonla and nitrogen oxide into the water, and

employing energy of the stored water for moving it to the soil, while controlling the ration of nitric oxide and ammonia and the pH of the water according to the needs of plants and soil.

9. The method oi irrigating which comprises partially oxidizing ammonia to nitrogen oxide, passing the oxidation products into water, and utilizing the water for irrigation, while controlling the oxidizing step to determine the pH of the water and controlling the ration of treated water according to the needs oi plants and soil for fertilization and relative acidity.

10. The method of irrigation which comprises storing water, employing energy 01' the water for generating electricity, employing the electricity a for electrolyzing water to produce hydrogen and oxygen, burning the part of hydrogen with air and separating water whereby to produce nitrogen. combining another part of the hydrogen with the nitrogen to form ammonia, oxidizing the ammonia by the oxygen produced in the electrolysis to form nitrogen oxide, passing the nitrogen oxide into water and utilizing the treated water tor irrigation, while controlling the ration of nitrogen oxide and the pr! 0! the water according to the needs oiplants and soil.

ii. The method ot irrigating which comprises storing water, employing energy 0! the water for generating electricity, employing the electricity for. producing ammonia, passing the products into a circulating stream of water to successively increase the percentage of ammonia therein, withdrawinga part of the ammonia from the stream and oxidizing .a part thereof to form nitrogen oxide while controlling the ratio 01' ammonia and nitrogen oxide in the eiiluent, passing the emuent into water. and utilizing the treated water for irrigation while controlling the ration of nitrogen compounds therein to the needs of plants and soil, the control of the ratio oi. ammonia and nitrogen oxide being employed to determine a substantially optimum pH of the treated water for the desired ratio or nitrogen compounds.

12. The method of irrigating which comprises 7 

